Hydraulic power unit



Jan. 4, 1966 M. c. BOKELMAN HYDRAULIC POWER UNIT 3 Sheets-Sheet 1 Filed May 6, 1963 w zg Jan. 4, 1966 c, BQKELMAN 3,227,279

HYDRAULIC POWER UNIT Filed May 6, 1963 3 Sheets-Sheet 2 Jan. 4, 1966 M. c. BOKELMAN 3,227,279

HYDRAULIC POWER UNIT Filed May 6, 1963 Sheets-Sheet 5 97 FF-,9, 10, J2,

HI HI .17 Q4 16 7/ Ill United States Patent 3,227,279 HYDRAULIC POWER UNIT Marinus C. Bokelman, Studio City, Calif, assignor to Conair, Inc, Glendale, Calif., a corporation of California Filed May 6, 1963, Ser. No. 277,987 10 Claims. (Cl. 210-120) This invention relates to hydraulic systems and more particularly to an improved unit affording a complete source of hydraulic power.

The principal object of the invention is to provide an integrated, compact hydraulic power system comprising a reservoir, pressure creating means, pressure regulating means, filter means and a manually controlled bypass means arranged in a single body structure whereby portions of the walls bounding the fluid supply reservoir serve also in part to define the cavities in which certain of the above named units of the system are housed.

Another object of the invention is to provide a hydraulic power unit having the foregoing desirable characteristics and which in addition is small in size and light in weight by reason of which it is particularly desirable for use in aircraft.

A further object of the invention is to provide a hydraulic power system of the above character in which the various instrumentalities such as pressure regulators, filters and the like can be readily removed and replaced with coincident establishment of the appropriate fluid flow connections therewith.

With the foregoing objects in view together with such additional objects and advantages as may subsequently appear, the invention resides in the parts, and in the construction, combination and arrangement of parts described, by way of example, in the following specification of a presently preferred embodiment of the invention, reference being had to the accompanying drawings which form a part of said specification and in which drawings:

FIG. 1 is a side elevational view of a hydraulic power unit embodying the present invention,

FIG. 2 is an end elevational view as viewed from the right hand end of FIG. 1,

FIG. 3 is a top plan view having reference tothe position of the device in FIG. 1,

FIG. 4 is a bottom plan view, the pump component having been removed and the position occupied by it being indicated in broken lines,

FIG. 5 is an enlarged fragmentary sectional view taken on the line 5-5 of FIG. 2,

FIG. 6 is an enlarged fragmentary sectional view taken on the line 6-6 of FIG. 1, i

FIG. 7 is a fragmentary sectional view taken on the line 7-7 of FIG. 6,

FIGS. 8 and 9 are respectively, fragmentary top plan view-s taken on the line 88 and 99 of FIG. 6,

FIG. 10 is an enlarged transverse medial sectional view taken on the line 10-10 of FIG. 1,

FIG. 11 is a fragmentary plan view taken on the line 11-11 of FIG. 10,

FIG. 12 is an enlarged scale fragmentary top plan view of the body member of the device, the cover being removed therefrom,

FIG. 13 is a fragmentary sectional view taken on the line 13-13 of FIG. 12, and

FIG. 14 is a diagrammatic showing of the interrelation of the components of the power unit.

Referring to the drawings, the illustrated embodiment of the invention comprises a hollow body member 1 of generally circular exterior configuration as viewed in plan including a bottom wall 2 having openings therein to which reference will hereinafter be made, and a side ICC Wall 3 on the exterior of which, except for interruptions to be noted hereafter, is provided with heat radiating ribs or fins 4. The top of the body member 1 is closed by a shallow, domed cover 5 removably secured thereon by screws 6 extending through the edge of the cover and threadedly engaging threaded holes 7 in the upper face of the side wall 3. The joint of the cover 5 with the body 1 is maintained leakproof by a gasket ring 8 disposed in a groove 9 in the edge of the cover 5 inwardly of the screw 6. The cover 5 is further provided with a filler opening 10 closed by a screw plug 11 and with a pressure relief valve unit 12 to which further reference will be made and so far as is possible, the exterior of the cover is provided with heat radiating fins 13. The interior of the body 1 constitutes the reservoir component of the unit and the level of the fiuid therein can be observed through an opening 14 in the side wall 3 of the body, which opening is closed by a sight glass 15 engaging a gasket 16 and held there against by a plate 17 secured by screws 18 and said plate having an opening 19 so disposed therein as to make the permissible upper and lower limits of fluid supply within the reservoir observable. Additionally, the body is provided with an outwardly extending cylindrical boss 20 having an axial bore 21 extending therethrough into the reservoir and con stituting an outlet or power port said bore being internal- 1y threaded for connection to the hydraulic conduit C1 leading to a hydraulic cylinder or other motor to be actuated. The body 1 is further provided with a similar boss 22 having a similarly internally threaded axial bore 23 affording connection with a return flow conduit C2 of the hydraulic system served by the unit said return port having communication directly with the interior of the reservoir.

The bottom wall 2 has a large sectoral opening 24 extending therewith as well as a smaller bore 25 extending upwardly from the outer face of the bottom wall 2 adjacent to the fiat side of the opening 24 and said bore 25 communicates with a bore 26 extending transversely of the bottom wall 2 within a rib portion 27 formed on the inner surface thereof, the outer end of said bore 26 being closed by a plug screw 28.

Fixed to the under side of the body 1 by screws 29 threaded into the bottom wall 2 is the connecting flange 3 of a pump mechanism generally indicated at 31 and containing a rotor means 32 adapted to be driven by power applied to a drive shaft 33. The pump body 31 has an intake port 34 communicating with the opening 24 and a discharge port 35 communicating with the bore 25 and the face of the flange portion 39 contacting the under face of the wall 2 is provided with the groove 36 surrounding both the opening 24 and the bore 25 and with a second groove 37 encircling the bore 25 within the perimeter of the groove 36. Gaskets 38 and 39 within the respective grooves serve to seal the two connections between the pump and the body member 1 and between these connections and the exterior of the unit. The pump is a standard article of commerce and further detailed description is not deemed to be required except to note that the pump body is provided with a peripheral flange 4-0 affording means whereby the pump and the unit constituting the present'invention thus carried by the pump may be expeditiously mounted on an aircraft.

At a point generally opposite the ports 21 and 23, the side wall 3 is made much thicker than at other points therealong to aiford room for three cylindrical cavities extending upwardly into said thickened portion of the wall from the bottom face of the body 1 and comprising a first cavity 41 in which a pressure regulator 42 is received, a second cavity 43 in which a filter unit 44 is received, and a third cylindrical cavity 45 in which a solenoid operated by-pass valve unit 46 is received. Additionally, the body member 1 at said thickened portion of the wall 3 thereof is provided with a generally radially inwardly extending cylindrical cavity 47 which is in communication with the flow of pressure fluid downstream from the filter unit and into which cavity the pressure sensing element 48 of a pressure switch 49 extends, the pressure switch having a flange 50 secured to the exterior of the wall 3 by screws 51 and having an O-ring gasket means 52 fitting the wall of the cavity 47 to prevent leakage.

In use, assuming that the reservoir and system are filled and that the pump 31 is operated, fiuid is being discharged into the passage 26 and thence into the upwardly extending passage 53 which is drilled into the thickened portion of the wall 3 inwardly of the cavity 41 said upwardly extending passage being closed at its lower end by a plug screw 54. The upper end of the passage 53 is connected by a short horizontal passage 55 with an annular space 56 which communicates with the inlet port 57 of the pressure regulator unit 42; said space being defined by upper and lower O-rings 58 and 59 on the pressure regulator body. Up to system pressure, the fluid passes through the regulator to the annular space 60 at the upper end of the cavity 41 which is sealed off by the O-ring 58. When the pressure exceeds required system pressure, the regulator diverts the fluid out of the port 61 into the annular space 62 defined by the O-rings 59 and 63 and the fluid thence is conducted through passage 64 back into the reservoir; said last named passage extending horizontally along the side of said annular space 62 through the wall of the body 1 and being closed at the outer end thereof by a plug screw 65.

Pressure fluid going into the system from the pressure regulator passes through a downwardly inclined bore 66 extending between the annular space 60 to an annular space 67 in the filter containing cavity 43 which is defined by O-rings 68 and 69 and thence percolates through a filter element 70 and through an upwardly directed port 71 in the filter device 44 into a cylindrical space 72 at the upper end of the cavity 43 which is sealed off by the O-ring 68. The filtered pressure fluid, when required by the system, passes from the space 72 to the port 21 through a passage 73 formed in the thickened portion of the body Wall 3 into a tube 74 having one end thereof inserted in a counterbore 75 formed as an extension of said passage 73 and said tube thence extending substantially diametrically across the upper portion of the reservoir cavity to a corresponding bore 76 formed in the wall 3 of the body member. O-rings 77 and 78 seated in grooves in the exterior of the tube 74 at each end thereof engage respectively, the counterbore 75 and the bore 76 to seal oif the interior of the tube from leakage into the reservoir and a threaded plug 79 having a cylindrical end 89 and an axial bore 81 is threaded into the port 21 to seat the tube against the bottom of the counterbore 75 and simultaneously afford communication with the fluid conduit means C1.

The space 72 is also connected by a passage 83 with the pressure switch cavity 47 said pressure switch being opened at all times when the apparatus is operating at system pressure and being closed to energize a light or other signal when the pressure is below the required system pressure. The cavity 47 is also connected by passage 84 with the fluid containing portion 85 of the solenoid operated valve cavity 45 and particularly with the annular space thereof which is above the O-ring 86. When the solenoid component 87 is energized by circuit means not shown, the valve means, which is normally closed, is opened to allow pressure fluid to pass thcrethrough and out of the discharge port 88 into the annular space 89 defined by the O-rings 86 and 90 and thence through passage 91 back into the reservoir. The purpose of this solenoid operated by-pass valve is to permit the unit and system served thereby to be temporarily disabled without,

4 however, stopping action of the pump so that the system components normally operated by the hydraulic pressure can be operated by manual means or by other power means.

Since the total volume of fluid is small and is being substantially constantly circulated through the unit at high pressure, a considerable amount of heat is generated, wherefore the body and cover are provided with the heat dissipating ribs or fins to which reference has heretofore been made. The unit is particularly designed for use in operating helicopter controls wherefore compactness and light weight are of prime importance. In this connection, the solenoid operated by-pass valve described is particularly useful where it is desired momentarily to substitute manual control for the power control.

There remains to be described the pressure relief valve on the cover element 5. This valve comprises a valve cage component 92 screwed into the threaded hole 93 in the cover 5; said valve cage having an axial bore extending therethrough including a smaller bore 94 at the inner end within the cover, an upwardly and outwardly tapered valve seat 95 extending from the outer end of the bore 94 to a larger bore 96, and an internally threaded portion 97 at the outer end of the larger bore 96. A valve member 98 is slidable in the bore 96 and is provided with a frusto-conical valve face 99 yieldingly pressed against the seat by a compression spring 100 which reacts against the end of a threaded plug 101 screwed into the threaded portion 97 and which is adjustable therein to vary the force exerted by the spring 100 on the valve member 98. Above the upper end of the valve member 98, the bore 96 is provided with a lateral port 102 affording communication with atmosphere.

The force exerted by the spring 100 is adjusted so that the valve member 98 will allow the escape of any pressure of the air which is above the fluid in the reservoir and which is greater than atmospheric pressure at sea level whereby, regardless of changes in altitude, a constant predetermined air pressure is maintained on the fluid in the reservoir.

Attention is now directed specifically to the fact that the present invention provides a most compact hydraulic power unit characterized by a compact arrangement of reservoir, the various instrumentalities of a hydraulic power unit such as a pressure regulator, a filter, a pressure responsive switch to indicate pressure failure and a means to disable the unit and system to allow other means to operate the devices normally operated by the unit, it being noted that such disabling is arranged to permit the flow of fluid into and out of the hydraulic motors of the system incident to movement thereof by the substituted operating means and it being noted further, that the unitary body construction also affords conduit communications between the various instrumentalities of the unit. Still further, it is to be noted that all of these various instrumentalities are mounted on the unit as individual subassemblies and hence are readily interchangeable and that the insertion of each of these subassemblies automatically effects the various connections with the appropriate fluid passages in the body structure and this capacity for quick interchange of these elements is an item of great importance in servicing aircraft and helicopters.

While in the foregoing specification there has been disclosed a presently preferred embodiment of the invention, such disclosure has been made by way of example and it will be understood that the invention is not to be deemed to be limited to the specific details thus disclosed and thatv the invention includes as well all such changes and modifications in the parts and in the construction, combina tion and arrangement of parts as shall come Within the purview of the appended claims.

I claim:

1. In a hydraulic power unit, a hollow body constituting a fluid reservoir, a pump attached to said body and.

having an intake port in direct communication with fluid in said reservoir and also having a discharge port, a pressure regulator and a fluid filter separately housed in cavities formed in said hollow body, fluid conduit means in said body connecting said pump discharge port with the inlet side of said pressure regulator and the outlet side of said pressure regulator with the inlet side of said fluid filter, other fluid conduit means connecting the outlet side of said fluid filterwith a pressure fluid port formed in a wall of said body for connection to a hydraulic motor means, a pressure responsive switch mounted on said body and including a pressure sensitive actuating component exposed to the pressure of fluid issuing from the outlet side of said fluid filter, and a normally closed solenoid operated valve interposed in another fluid conduit means formed in said body and extending between the fluid outlet side of said fluid filter and the interior of said reservoir.

2. A hydraulic power unit as claimed in claim 1 in which the interengagement of said pressure regulator and said fluid filter with their respective cavities includes means affording separate communication between the inlet and outlet sides of said pressure regulator and said fluid filter with the appropriate ones of said conduit means regardless of the rotative positions of the pressure regulator and the fluid filter in their respective cavities.

3. A hydraulic power unit as claimed in claim 1 in which said cavity housing said pressure regulator is cylindrical in form and in which the body of said pressure regulator within said cavity is provided with an inlet port, an outlet port, and a bypass port, and is cylindrical and of lesser diameter than said cavity and, further, is provided with a plurality of O-ring gaskets engaging said cavity at axially spaced intervals and dividing the space between said pressure regulator and cavity into a series of annular spaces separately affording communication of the appropriate ones of said fluid conduit means with the inlet port, the outlet port and the bypass port of said pressure regulator, respectively.

4. A hydraulic power unit as claimed in claim 1 in which said cavity for said fluid filter is cylindrical in form and in which the portion of said fluid filter within said cavity is of lesser diameter than said cavity and is i provided with O-ring gasket means engaging the wall of said cavity to divide the portion of said cavity between the filter and the cavity into annular spaces aflording communication between the appropriate ones of said fluid conduit means with the fluid inlet and fluid outlet sides of said fluid filter, respectively.

5. A hydraulic power unit as claimed in claim 1 in which said hollow body member additionally includes means eflective normally to maintain a predetermined magnitude of air pressure on the fluid in said reservoir regardless of external atmospheric pressure changes deriving from changes in altitude.

6. A hydraulic power unit as claimed in claim 5 in which the top of said hollow body is provide with normally closed check valve means biased to maintain a predetermined maximum air pressure imposed on fluid in said reservoir.

7. In a hydraulic power unit, a hollow body including i a bottom wall, a peripheral side Wall, and a detachable cover and constituting a fluid reservoir, a pressure fluid port in said side wall affording means for connection of conduit means extending to a motor to be operated by said unit, a return port in said side wall afiording means for connection of conduit means returning fluid to said reservoir, a pump attached to said reservoir having an intake port means in direct communication with the interior of said reservoir and also having a discharge port, first, second, third and fourth cavities formed in said side wall and housing, respectively, a pressure regulator having an inlet port, an outlet port, and a bypass port, a filter having an irflet port and an outlet port, a pressure responsive switch, and a solenoid operated bypass valve having an inlet port and an outlet port, a first conduit means formed in the walls of said hollow body extending from the discharge port of said pump to said first cavity and affording communnication with the inlet port of said pressure regulator, a second conduit means formed in a wall of said body and extending between said first and second cavities affording communication between the outlet port of said pressure regulator and the inlet port of said filter, a third conduit means contained within said hollow body and extending from said second cavity to said pressure fluid port and connecting said outlet port of said filter with said pressure fluid port, a fourth conduit means in said side wall extending between said second and third cavities and operative to impose the pressure of fluid downstream of said filter on the pressure sensing means of said pressure responsive switch, a fifth conduit means in said side wall extending between said third and fourth cavities and connecting said third cavity with the inlet port of said solenoid operated bypass valve, a first fluid passage in said side wall connecting the bypass port of said pressure regulator with said reservoir, and a second fluid passage in said side wall connecting the outlet port of said bypass valve with said reservoir.

8. A hydraulic power unit as claimed in claim 7 in which means is provided in said first cavity dividing the space therein into spaces affording communication between the ports of said pressure regulator with the appropriate fluid conduit means.

9. A hydraulic power unit as claimed in claim 7 in which means is provided in said second cavity dividing the space therein into spaces affording communication of the fluid inlet and outlets of said filter with the appropriate ones of said fluid conduit means.

10. A hydraulic power unit as claimed in claim 7 in which said pressure responsive switch is biased to remain open in the presence of pressure less than operating pressure of said unit.

References Cited by the Examiner UNITED STATES PATENTS 2,119,740 6/1938 Fellows et al 137115 X 2,460,058 1/1949 Brodeur 103220 X 2,880,674 4/ 1959 Klessig et al -42 REUBEN FRIEDMAN, Primary Examiner.

F. A. SPEAR, Assistant Examiner. 

1. IN A HYDRAULIC POWER UNIT, A HOLLOW BODY CONSTITUTING A FLUID RESERVOIR, A PUMP ATTACHED TO SAID BODY AND HAVING AN INTAKE PORT IN DIRECT COMMUNICATION WITH FLUID IN SAID RESERVOIR AND ALSO HAVING A DISCHARGE PORT, A PRESSURE REGULATOR AND A FLUID FILTER SEPARATELY HOUSING IN CAVITIES FORMED IN SAID HOLLOW BODY, FLUID CONDUIT MEANS IN SAID BODY CONNECTING SAID PUMP DISCHARGE PORT WITH THE INLET SIDE OF SAID PRESSURE REGULATOR AND THE OUTLET SIDE OF SAID PRESSURE REGULATOR WITH THE INLET SIDE OF SAID FLUID FILTER, OTHER FLUID CONDUIT MEANS CONNECTING THE OUTLET SIDE OF SAID FLUID FILTER WITH A PRESSURE FLUID PORT FORMED IN A WALL OF SAID BODY FOR CONNECTION TO A HYDRAULIC MOTOR MEANS, A PRESSURE RESPONSIVE SWITCH MOUNTED ON SAID BODY AND INCLUDING A PRESSURE SENSITIVE ACTUATING COMPONENT EXPOSED TO THE PRESSURE OF FLUID ISSUING FROM THE OUTLET SIDE OF SAID FLUID FILTER, AND A NORMALLY CLOSED SOLENOID OPERATED VALVE INTERPOSED IN ANOTHER FLUID CONDUIT MEANS FORMED IN SAID BODY AND EXTENDING BETWEEN THE FLUID OUTLET SIDE OF SAID FLUID FILTER AND THE INTERIOR OF SAID RESERVOIR. 